Process for the preparation of aminoalcohol derivatives and their further conversion to (1r, 4s)-4(2-amino-6-chloro-5-formamido-4- pyrimidinyl)-amino-2-cyclopentenyl-1-methanol

ABSTRACT

The invention relates to a novel process for the preparation of an aminoalcohol of the formula  
                 
 
racemically or optically active, starting from 2-azabicyclo[2.2.1]hept-5-en-3-one, its further conversion to give the corresponding acyl derivative and its further conversion to (1S,4R)- or (1R,4S)-4-(2-amino-6-chloro-9-H-purine-9-yl)-2-cyclopentenyl-1-methanol of the formulae  
                 
 
In the latter synthesis, the aminoalcohol is converted into the corresponding D- or L-tartrate, which is then reacted with N-(2-amino-4,6-dichloropyrimidin-5-yl)formamide of the formula  
                 
 
to give (1S,4R)- or (1R,4S)-4-[(2-amino-6-chloro-5-formamido-4-pyrimidinyl)amino]-2-cyclopentenyl-1-methanol of the formulae  
                 
and then cyclized to give the end compounds.

The present invention relates to a novel process for the preparation of(1R,4S)- or (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene of theformulae

or salts thereof, or the D- or L-hydrogentartrates thereof and alsotheir further conversion to give (1S,4R)- or(1R,4S)-4-(2-amino-6-chloro-9-H-purine-9-yl)-2-cyclopentene.(1R,4S)-1-Amino-4-(hydroxymethyl)-2-cyclopentene of the formula IV is animportant intermediate for the preparation of carbocyclic nucleosidessuch as, for example, Carbovir® (Campbell et al., J. Org. Chem. 1995,60, 4602-4616).

A process for the preparation of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene is described, forexample, by Campbell et al. (ibid) and by Park K. H. & Rapoport H. (J.Org. Chem. 1994, 59, 394-399).

In this process, the starting material is either D-glucono-δ-lactone orD-serine, approximately 15 synthesis stages being required to form(1R,4S)-N-tert-butoxy-carbonyl-4-hydroxymethyl-2-cyclopentene, and theprotecting group is removed to give(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene.

Both these processes are costly, complex and not practicableindustrially. WO 93/17020 describes a process for the preparation of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene, in which(1R,4S)-4-amino-2-cyclopentene-1-carboxylic acid is reduced to thedesired product using lithium aluminium hydride.

Disadvantages of this process are firstly that the double bond of thecyclopentene ring is also reduced, the poor handling properties oflithium aluminium hydride and secondly that it is too costly.

Taylor S. J. et al. (Tetrahetron: Asymmetry Vol. 4, No. 6, 1993,1117-1128) describe a process for the preparation of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene starting from(±)-2-azabicyclo[2.2.1]hept-5-en-3-one as starting material. In thisprocess, the starting material is converted, using microorganisms of thespecies Pseudomonas solanacearum or Pseudomonas fluorescens, into(1R,4S)-2-azabicyclo[2.2.1]hept-5-en-3-one, which is then reacted withdi-tert-butyl dicarbonate to give(1R,4S)-N-tert-butoxycarbonyl-2-azabicyclo[2.2.1]hept-5-en-3-one, andthe latter is reduced using sodium borohydride and trifluoroacetic acidto give the desired product.

This process is far too costly.

In addition, Martinez et al. (J. Org. Chem. 1996, 61, 7963-7966)describe a 10-stage synthesis of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene starting from diethyldialkylmalonate. This process too has the disadvantage that it iscomplex and not practicable industrially.

It is also known that N-substituted(±)-2-azabicyclo-[2.2.1]hept-5-en-3-ones, which carry anelectron-with-drawing substituent, can be reduced to the correspondingN-substituted aminoalcohols using a metal hydride (Katagiri et al.,Tetrahedron Letters, 1989, 30, 1645-1648; Taylor et al., ibid).

In contrast to this, it is known that unsubstituted(±)-2-azabicyclo[2.2.1]hept-5-en-3-one of the formula

is reduced with lithium aluminium hydride to give(±)-2-azabicyclo[2.2.2]octene (Malpass & Tweedle, J. Chem. Soc., PerkinTrans 1, 1977, 874-884), and that the direct reduction of(±)-2-azabicyclo[2.2.2]hept-5-en-3-one to give the correspondingaminoalcohol has to date been impossible (Katagiri et al., ibid; Tayloret al., ibid).

It is also known to resolve racemic1-amino-4-(hydroxymethyl)-2-cyclopentene using (−)-dibenzoyltartaricacid (U.S. Pat. No. 5,034,394). On the one hand, this reaction has thedisadvantage that (−)-dibenzoyltartaric acid is expensive, and, on theother hand, that the separation must take place in the presence of anexactly defined mixture of acetonitrile and ethanol. This solventmixture cannot be removed and must be fed to the combustion.

The object of the present invention was to provide a simple, economicaland cost-effective process for the preparation of a(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene.

Surprisingly, it has now been found that when(±)-2-azabicyclo[2.2.1]hept-5-en-3-one of the formula

in the form of the racemate or one of its optically active isomers, isreduced with a metal hydride, the aminoalcohol of the formula

in the form of the racemate or one of its optically active isomers isobtained in a simple manner.

As the person skilled in the art is aware, the aminoalcohol of theformula I can be converted using an acid into the corresponding salts,such as, for example, into hydrohalide salts. Suitable hydrohalide saltsare hydrobromides and hydrochlorides.

The starting material, the (±)-2-azabicyclo-[2.2.1]hept-5-en-3-one canbe prepared according to EP-A 0 508 352.

Metal hydrides which may be used are alkali metal or alkaline earthmetal hydrides and also binary or complex metal hydrides of the boron oraluminium group, such as alkali metal and alkaline earth metalborohydrides, alkali metal and alkaline earth metal aluminium hydrides.Suitable alkali metal or alkaline earth metal hydrides are LiH, NaH, KH,BeH₂, MgH₂ or CaH₂.

Binary alkali metal or alkaline earth metal borohydrides which may beused are NaBH₄, LiBH4, KBH₄, NaAlH₄, LiAlH₄, KAlH₄, Mg(BH₄)₂, Ca(BH₄)₂,Mg(AlH₄)₂ and Ca(AlH₄)₂. Complex metal hydrides of the boron oraluminium group may have the general formula M¹M²H_(n)L_(m), in which nis an integer from 1 to 4, and m is an integer from 4 to 4 minus thecorresponding number n, M¹ is an alkali metal atom, M² is boron oraluminium, and L is C₁₋₄-alkyl, C₁₋₄-alkenyl, C₁₋₄-alkoxy, CN or anamine, or the complex metal hydrides may have the general formulaM²H_(O)L_(p), in which M² is as defined above and O is an integer from 0to 3, and p is an integer from 3 to 3 minus the corresponding number p.Possible M¹M²H_(n)L_(m) compounds are LiBH(C₂H₅)₃, LiBH_(x)(OCH₃)_(4-x),LiAlH(OC(CH₃)₃)₃, NaAlH₂(OC₂H₄OCH₃)₂, NaAlH₂(C₂H₅)₂ or NaBH₃CN.Preferably, the reduction is carried out using a metal borohydride. Asan expert in the art is aware, the metal hydrides mentioned such as, forexample, LiBH₄, can also be produced “in situ”. Common preparationmethods for LiBH₄ are, for example, the reaction of an alkali metalborohydride with a lithium halide (H. C. Brown et al., Inorg. Chem. 20,1981, 4456-4457), the reaction of LiH with B₂O₃ in the presence ofhydrogen and a hydrogenation catalyst (EP-A 0 512 895), the reaction ofLiH with (H₅C₂)OBF₃ (DE-A 94 77 02) and that of LiH with B(OCH₃)₃ (U.S.Pat. No. 2,534,533).

The metal hydrides are expediently used in a molar ratio of from 1 to 5per mole of (±)-2-azabicyclo-[2.2.1]hept-5-en-3-one.

The metal hydrides, in particular NaBH₄, are preferably used withlithium salt additives. Lithium salts which may be used are LiCl, LiF,LiBr, LiI, Li₂SO₄, LiHSO₄, Li₂CO₃, Li(OCH₃) and LiCO₃.

The reduction is expediently carried out in an inert-gas atmosphere,such as, for example, in an argon or nitrogen atmosphere.

The reduction can be carried out at a temperature of from −20 to 200°C., preferably at a temperature of from 60 to 150° C.

Suitable solvents are aprotic or protic organic solvents. Suitableaprotic organic solvents may be ethers or glycol ethers, such as, forexample, diethyl ether, dibutyl ether, ethyl methyl ether, diisopropylether, tert-butyl methyl ether, anisole, dioxane, tetrahydrofuran,monoglyme, diglyme and formaldehyde dimethylacetal. Suitable proticorganic solvents are C₁₋₆-alcohols, such as methanol, ethanol, propanol,isopropanol, butanol, tert-butanol, pentanol, tert-amyl alcohol orhexanol and also mixtures of these with water. Suitable protic organicsolvents are also mixtures of one of said ethers, glycol ether withwater or with one of said alcohols, such as a mixture of a C₁₋₆-alcoholwith an ether or glycol ether, in particular a mixture of methanol,ethanol or water with diethyl ether, tetrahydrofuran, dioxane, glyme ordiglyme. The solvent used is preferably a protic organic one, such as amixture of a C₁₋₆-alcohol or water with an ether or glycol ether.

In a preferred embodiment, the reduction is carried out in the presenceof an additive, such as in the presence of water or of a lower aliphaticalcohol. The lower aliphatic alcohol may be methanol, ethanol,methoxyethanol, n-propanol, isopropanol, isobutanol, tert-butanol,n-butanol, diols such as butanediol, and triols such as glycerol. Inparticular, the lower aliphatic alcohol is methanol or ethanol. Here,the lower aliphatic alcohol is expediently used in a molar ratio of from2 to 15 per mol of (±)-2-azabicyclo[2.2.1]hept-5-en-3-one.

If the reaction is carried out in the presence of said alcohol, thecorresponding amino acid ester can be formed in situ (intermediate).I.e. if the starting material used is(±)-2-azabicyclo[2.2.1]hept-5-en-3-one, according to the invention thecorresponding (±)-amino acid ester can be formed. If the startingmaterial used is (−)-2-azabicyclo[2.2.1]hept-5-en-3-one, according tothe invention the (−)-amino acid ester can correspondingly be formed asintermediate.

Surprisingly, it has also been found that when a cyclopentene derivativeof the general formula

in the form of the racemate or one of its optically active isomers, inwhich R is C₁₋₄-alkyl, C₁₋₄-alkoxy, aryl or aryloxy, is hydrolyzed withan alkali metal hydroxide, the aminoalcohol of the formula

in the form of the racemate or one of its optically active isomers isobtained in a simple manner.

C1-4-Alkyl can be substituted or unsubstituted. In the text belowsubstituted C₁₋₄-alkyl is taken to mean C₁₋₄-alkyl substituted by ahalogen atom. The halogen atom may be F, Cl, Br or I. Examples ofC₁₋₄-alkyl are methyl, ethyl, propyl, butyl, isobutyl, tert-butyl,isopropyl, chloromethyl, bromomethyl, dichloromethyl and dibromomethyl.The C₁₋₄-alkyl is preferably methyl, ethyl, propyl, butyl, isobutyl orchloromethyl.

The C₁₋₄-alkoxy used may be, for example, methoxy, ethoxy, propoxy orbutoxy. The aryl used can be, for example, phenyl or benzyl, substitutedor unsubstituted. The aryloxy used can be, for example, benzyloxy orphenoxy, substituted or unsubstituted.

The alkali metal hydroxide used may be sodium or potassium hydroxide.

For this process variant, the cyclopentene derivative of the generalformula III is preferably prepared by reduction of the correspondingacyl-2-azabicyclo[2.2.1]hept-5-en-3-one of the general formula

in the form of the racemate or one of its optically active isomers, inwhich R is as defined above, using one of the metal hydrides alreadymentioned in an anhydrous solvent.

The anhydrous solvent may be protic or aprotic organic solvents, inparticular an anhydrous protic organic solvent such as a tertiaryalcohol. The tertiary alcohol may be tert-butyl alcohol or tert-amylalcohol.

As already mentioned above, this reduction is also preferably carriedout in the presence of an addition, such as in the presence of a loweraliphatic alcohol such as methanol, in particular in the presence of 2mol of methanol per mole of acyl-2-azabicyclo-[2.2.1]hept-5-en-3-one(formula IV).

The reaction is expediently carried out at a temperature of from 0 to50° C., preferably from 15 to 30° C.

The racemic aminoalcohol of the formula I is then converted according tothe invention either by chemical means using an optically activetartaric acid or by biotechnological means using a hydrolase in thepresence of an acylating agent to give (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene of the formula

or salts thereof and/or to give (1S,4R)- or(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene derivative of thegeneral formulae

or salts thereof, in which X and Y are identical or different and are anacyl group or H. with the exception of X=Y=H.

The hydrolases used may be lipases, proteases, amidases or esterases,lipases being expediently used.

In the text below, salts are taken to mean hydrohalide salts such ashydrochlorides, hydrobromides or tartrates.

As the person skilled in the art is aware, hydrolase-catalyzedacylations in which optically active compounds are formed are carriedout in the presence of a suitable acylating agent (Balkenhohl et al.,1997, J. Prakt. Chem. 339, 381-384; K. Faber, “Biotransformation inOrganic Chemistry”, 2nd ed., Berlin 1995, 270-305). Suitable acylatingagents are generally carboxylic acid derivatives such as carboxamides,carboxylic anhydrides or carboxylic esters. The carboxylic esters may,for example, be alkoxycarboxylic esters, such as ethyl methoxyacetateand isopropyl methoxyacetate, C₁₋₆-carboxylic esters, such as butylacetate, ethyl butyrate and ethyl hexanoate, glyceryl esters, such astributyrin (glyceryl tributyrate), glycol esters, such as glycoldibutyrate and diethyl diglycolate, dicarboxylic esters, such as diethylfumarate and malonate, cyanocarboxylic esters, such as ethylcyanoacetate, or cyclic esters, such as, for example, 6-caprolactone.

Accordingly, the acyl group in the formulae VII and VIII corresponds tothe acid component of the carboxylic acid derivative used.

The lipases used may be standard commercial lipases, such as, forexample: Novo lipase SP523 from Aspergillus oryzae (Novozym 398), Novolipase SP524 from Aspergillus oryzae (lipase=Palatase 20000 L fromNovo), Novo lipase SP525 from Candida antarctica (lipase B Novozym 435,immobilized), Novo lipase SP526 from Candida antarctica (lipaseA=Novozym 735, immobilized), lipase kits from Fluka (1 & 2), Amano Plipase, lipase from Pseudomonas sp., lipase from Candida cylindracea,lipase from Candida lypolytica, lipase from Mucor miehei, lipase fromAspergillus niger, lipase from Bacillus thermocatenulatus, lipase fromCandida antarctica, lipase AH (Amano; immobilized), lipase P (Nagase),lipase AY from Candida rugosa, lipase G (Amano 50), lipase F (AmanoF-AP15), lipase PS (Amano), lipase AH (Amano), lipase D (Amano), lipaseAK from Pseudomonas fluorescens, lipase PS from Pseudomonas cepacia,newlase I from Rhizopus niveus, lipase PS-CI (immobilized lipase fromPseudomonas cepacia). These lipases may, as the person skilled in theart is aware, be used as cell-free enzyme extracts or else in thecorresponding microorganism cell.

The proteases may also be commercially available, such as, for example,serine proteases such as subtilisins. The subtilisin may be savinasefrom Bacillus sp., alcalase, subtilisin from Bacillus licheniformis andalso proteases from Aspergillus, Rhizopus, Streptomyces or Bacillus sp.

The biotechnological racemate resolution is expediently carried out at atemperature of from 10 to 80° C. and at a pH of from 4 to 9.

The biotechnological racemate resolution is expediently carried out in aprotic or aprotic organic solvent. Suitable aprotic organic solvents areethers such as tert-butyl methyl ether, diisopropyl ether, dibutylether, dioxane and tetrahydrofuran, aliphatic hydrocarbons such ashexane, organic bases such as pyridine, and carboxylic esters such asethyl acetate, and suitable protic organic solvents are theC₁₋₆-alcohols already described, such as, for example, pentanol.

The (1S,4R)- or (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentenederivatives of the general formulae VII and VIII formed in accordancewith the invention during the biotechnological racemate resolution are,depending on the desired target compound (aminoalcohol of the formula Vor VI), hydrolyzed by chemical means to give the aminoalcohol of theformula V or VI. The chemical hydrolysis is expediently carried out inan aqueous basic solution or using a basic ion exchanger. The aqueousbasic solution is preferably, as for the hydrolysis of the cyclopentenederivatives of the general formula III described above, an alkali metalhydroxide. The basic ion exchangers can, for example, be Dowex 1×8(OH⁻)and Duolite A147.

The chemical racemate resolution is carried out using an opticallyactive tartaric acid such as using D-(−)-tartaric acid or L-(+)-tartaricacid.

The racemate resolution with D-(−)-tartaric acid is expediently carriedout by firstly reacting the racemic1-amino-4-(hydroxymethyl)-2-cyclopentene with the D-(−)-tartaric acid inthe presence of a lower aliphatic alcohol.

Suitable lower aliphatic alcohols are the same as those described above.Preference is given to using methanol. The reaction which leads toformation of the salt is usually carried out at temperature between 20°C. and the reflux temperature of the solvent, preferably at the refluxtemperature.

If desired, the 1-amino-4-(hydroxymethyl)-2-cyclopentene D-tartrateformed during the reaction can be further purified by recrystallizationfrom a lower aliphatic alcohol such as methanol.

The racemate resolution with L-(+)-tartaric acid is expediently carriedout as that with D-(−)-tartaric acid. I.e. the racemate resoluton withL-(+)-tartaric acid is likewise carried out in the presence of a loweraliphatic alcohol and at a temperature between 20° C. and the refluxtemperature of the solvent, preferably at the reflux temperature. Aftercooling, the (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopenteneL-hydrogentartrate crystallizes out.

The (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene L-hydrogentartrateis present, in particular, in dissolved form in the mother liquor.

Isolation, further purification (liberation) and conversion to thecorresponding salt of (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene takes place with a baseand subsequent acid treatment. Suitable bases are alkali metalalkoxides, alkali metal or alkaline earth metal carbonates, or alkalimetal or alkaline earth metal hydroxides. The alkali metal alkoxides maybe sodium or potassium alkoxides. The alkali metal carbonate may bepotassium or sodium carbonate, potassium or sodium hydrogencarbonate,and the alkaline earth metal carbonate may be magnesium or calciumcarbonate. The alkali metal hydroxide may be sodium or potassiumhydroxide, and the alkaline earth metal hydroxide may be calciumhydroxide. Conversion to the corresponding salt usually takes place witha mineral acid such as with sulphuric acid, hydrochloric acid orphosphoric acid, preferably with hydrochloric acid.

(1R,4S)- or (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopenteneD-hydrogentartrate and (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene L-hydrogentartrate arecompounds unknown in the literature and are likewise provided by theinvention.

Preference is given to carrying out the chemical racemate resolutionwith D-(+)-tartaric acid due to the higher performance, technicalfacility and more efficient racemate resolution.

As for the racemic aminoalcohol, it is of course also possible to reactthe optically active (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentenes with D-(−)- orL-(+)-tartaric acid to give the corresponding tartrates.

A further constituent of the present invention is the furtherconversion, the acylation, of the (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentenes to give the(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene derivative of thegeneral formula

Here, the substituent R is as defined in the cyclopenten derivative ofthe general formula III.

The acylation can be carried out using a carbonyl halide of the generalformula

in which X is a halogen atom, and R is as defined above, or using acarboxylic anhydride of the general formula

in which R is as defined above.

The halogen atom X may be F, Cl, Br or I. Preference is given to Cl orF.

Examples of carbonyl halides are: acetyl chloride, chloroacetylchloride, butyryl chloride, isobutyryl chloride, phenylacetyl chloride,benzyl chloroformate, propionyl chloride, benzoyl chloride, alkylchloroformate or tert-butyloxycarbonyl fluoride.

Examples of carboxylic anhydrides are: tertbutoxycarbonyl anhydride,butyric anhydride, acetic anhydride or propionic anhydride. Theacylation is preferably carried out using a carboxylic anhydride, inparticular using tert-butoxycarbonyl anhydride.

The acylation can be carried out without solvent or using an aproticorganic solvent. The acylation is expediently carried out in an aproticorganic solvent. Suitable aprotic organic solvents are, for example,pyridine, acetonitrile, dimethylformamide, diisopropyl ether,tetrahydrofuran, toluene, methylene chloride, N-methylpyrrolidone,triethylamine, chloroform, ethyl acetate, acetic anhydride and mixturesthereof.

The acylation is expediently carried out at a temperature of from −20 to100° C., preferably from 0 to 80° C.

The further conversion according to the invention of (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene D- orL-hydrogentartrate to (1S,4R)- or(1R,4S)-4-(2-amino-6-chloro-9-H-purine-9-yl)-2-cyclopentenyl-1-methanol,or a salt thereof, of the formulae

is carried out by reacting (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene D- orL-hydrogentartrate with N-(2-amino-4,6-dichloropyrimidin-5-yl)formamideof the formula

to give (1S,4R)- or(1R,4S)-4-[(2-amino-6-chloro-5-formamido-4-pyrimidinyl)amino]-2-cyclopentenyl-1-methanol of the formulae

and then cyclizing the latter in a known manner to give the compoundsaccording to formula VIII and IX.

N-(2-Amino-4,6-dichloropyrimidin-5-y1) formamide can be preparedaccording to WO 95/21 161.

The reaction is expediently carried out in the presence of a base.Suitable bases are the same as those previously described for liberating(1R,4S)- or (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentenes from thecorresponding tartrate.

The reaction is expediently carried out in a protic solvent. The proticsolvent may be lower aliphatic alcohols such as methanol, ethanol,propanol, isopropanol, butanol or isobutanol.

The (1S,4R)- or (1R,4S)-4-[(2-amino-6-chloro-5-formamido-4-pyrimidinyl)amino]-2-cyclopentenyl-1-methanol of the formula XI or XII is thencyclized in a known manner according to WO 95/21 161 to give the endproduct according to Formula VIII or IX.

The cyclization is usually carried out dissolved in trialkylorthoformate in the presence of a concentrated aqueous acid. Thetrialkyl orthoformates used may be, for example, trimethyl or triethylorthoformate.

The aqueous acid may be, for example, hydrogen fluoride, sulphuric acidor methanesulphonic acid.

A further constituent of the invention is the overall process for thepreparation of(1S,4R)-4-(2-amino-6-chloro-9-H-purine-9-yl)-2-cyclopentenyl-1-methanol,or salts thereof, of the formula XII starting from(−)-2-azabicyclo[2.2.1]hept-5-en-3-one or(−)-acyl-2-azabicyclo[2.2.1]hept-5-en-3-one of the formulae

in which R is as defined above, by reduction with a metal hydride togive an aminoalcohol of the formula

or to give a cyclopentene derivative of the general formula

in which R is as defined above, which are then converted into thecorresponding hydrohalide salts, and then reacted withN-(2-amino-4,6-dichloropyrimidin-5-yl)-formamide of the formula

to give(1S,4R)-4-[(2-amino-6-chloro-5-formamido-4-pyrimidinyl)amino]-2-cyclopentenyl-1-methanolof the formula

and then the latter is cyclized in a known manner to give the compoundof the formula

This process variant has the advantage that the hydrohalide salts formedtherein may be used as a crude mixture in the preparation of the productof the formula XII.

EXAMPLES Example 1 Reduction of acyl- orunsubstituted-2-azabicyclo[2.2.1]-hept-5-en-3-one 1.1. Preparation of(±)-acetyl-1-amino-4-(hydroxymethyl)-2-cyclopentene in an anhydrousprotic organic solvent using sodium borohydride

280 g of 2-methyl-2-butanol (amyl alcohol) and 15.2 g of sodiumborohydride (0.4 mol) were charged into a sulphonation flask at 20° C. Amixture of 907 g of (±)-acetyl-2-azabicyclo[2.2.1]hept-5-en-3-one (0.6mol) and 37.5 g of methanol (2 equivalents based on(±)-acetyl-2-azabicyclo[2.2.1]hept-5-en-3-one was metered into thissuspension over the course of 2 h at 20° C. The reaction mixture wasthen stirred for a further 3 h at 20° C. The solvent was distilled asfar as possible (40° C.). Boron was removed by adding 280 g of methanoland 27.2 g of formic acid, warming the mixture to 25-30° C. anddistilling off the methyl borate/methanol azeotrope at this temperature(130 to 80 mbar). The precipitated sodium formate was filtered off, andthe filtrate was reduced by evaporation to give 93.4 g of crude productas a clear viscous oil; crude yield: about 84-85%.

1.2. Preparation of cis-1-amino-4-(hydroxymethyl)-2-cyclopentene

A suspension of (+)-2-azabicyclo[2.2.1]hept-5-en-3-one (10.00 g, 91.6mmol) and lithium borohydride (4.00 g, 183.7 mmol) in dry dioxane (100ml) was heated in an inert-gas atmosphere (argon) for 4 h at 110° C.below the reflux temperature. After this time, about 20-25% of thestarting material had reacted to give the product (GC analysis withinternal standard benzophenone after work-up of the reaction mixture;work-up: 0.05 ml of the reaction mixture were quenched with 0.1 ml of 1M HCl and immediately rendered basic using 0.2 ml of 1 M NaOH). Thestructural detection of the product was carried out by H-NMR, GC andGC-MS.

1.3. Preparation of (+)-1-amino-4-(hydroxymethyl)-2-cyclopentene

A 25 ml round-bottom flask was charged with 1.0 g (9.2 mmol) of(+)-2-azabicyclo[2.2.1]hept-5-en-3-one and 0.4 g (18.4 mmol) of lithiumborohydride, under an inert-gas atmosphere, in 10 ml of dioxane, and themixture was refluxed for 3 h at 110° C. Excess reducing agent wasdestroyed by adding about 5 ml of semi-concentrated HCl (adjusted to pH3). The mixture was then immediately buffered by adding about 1 ml ofsaturated NaHCO₃ solution at pH 8. GC analysis indicated the formationof the product. The entire reaction mixture was then evaporated todryness and purified by means of column chromatography (gradient:hexane/ethyl acetate/MeOH=1:1:1→MeOH). In this way(+)-2-azabicyclo-[2.2.1]hept-5-en-3-one and the corresponding(+)-aminoalcohol were obtained.

1.4. Preparation of (−)-1-amino-4-(hydroxymethyl)-2-cyclopentene

A 25 ml round-bottom flask was charged with 1.0 g (9.2 mmol) of(−)-2-azabicyclo[2.2.1]hept-5-en-3-one and 0.4 g (18.4 mmol) of lithiumborohydride, under an inert-gas atmosphere, in 10 ml of dioxane, and themixture was refluxed for 3 h at 110° C. Excess reducing agent wasdestroyed by adding about 5 ml of semi-concentrated HCl (adjusted to pH3). The mixture was then immediately buffered by adding about 1 ml ofsaturated NaHCO₃ solution at pH 8. GC analysis indicated the formationof the product in 18% yield (GC standard is benzophenone). The entirereaction mixture was then evaporated to dryness and purified by means ofcolumn chromatography (gradient: hexane/ethyl acetate/MeOH=1:1:1→MeOH).In this way, 0.43 g (43%) of (−)-2-azabicyclo[2.2.1]-hept-5-en-3-one wasreisolated and 0.04 g (4%) of the corresponding (−)-aminoalcohol wasobtained.

By HPLC, only the (−)-enantiomer of the aminoalcohol was detectable. Theee of the product is thus >98%.

1.5. Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene in analcohol

A 100 ml round-bottom flask fitted with magnetic stirrer was chargedwith 3.0 g (27.5 mmol) of (±)-2-azabicyclo[2.2.1]hept-5-en-3-one and 1.2g (28.3 mmol) of lithium borohydride, under an inert-gas atmosphere, in35 g of 2-butanol, and the mixture was stirred for 3 h at 60° C. GCanalysis of a sample (work-up: 0.1 g sample rendered acidic using 0.2 mlof 1 M HCl, then quickly rendered basic using 0.1 ml of saturatedNaHCO₃) indicated the formation of the product in 12% yield after thistime. (GC standard is benzophenone.)

1.6. Preparation of a (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene in analcohol/ether mixture

A 10 ml round-bottom flask was charged under at inert-gas atmospherewith 0.5 g (4.6 mmol) of (±)-2-azabicyclo[2.2.1]hept-5-en-3-one and 0.59g (18.4 mmol) of methanol in 7.5 ml of dioxane (abs.). 0.21 g (9.2 mmol)of lithium borohydride were added, and the mixture was heated for 4 h at60° C. The mixture was then cooled to 520 C. using an ice/waterbath, andabout 10 ml of semi-concentrated HCl was carefully added to the reactionmixture (vigorous reaction, gas evolution), as a result of which ayellowish clear solution formed. This solution was analyzed directly bya quantitative ion-chromatographic method. It contained 0.60 mmol(13.1%) of (±)-2-azabicyclo[2.2.1]hept-5-en-3-one (determined as HClsalt of the corresponding amino acid, which is the acidic hydrolysisproduct of (±)-2-azabicyclo-[2.2.1]hept-5-en-3-one) and 3.06 mmol ofproduct, corresponding to a yield of 66.8%, aminoalcohol.

1.7. Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene in thepresence of additives such as water or various alcohols

A 10 ml round-bottom flask was charged with 0.50 g (4.66 mmol) of(±)-2-azabicyclo[2.2.1]hept-5-en-3-one and 0.30 g (13.7 mmol) of lithiumborohydride in 7.5 ml of abs. dioxane, and the mixture was heated to 60°C.

At this temperature, over the course of 30 min, X mmol of alcohol Y wasadded dropwise using a syringe. The mixture is then stirred for 2 h at60° C., cooled to about 20° C. and poured into about 10 ml ofsemi-concentrated HCl. The content was then determined directly using aquantitative ion-chromatographic method (cf. Table 1). TABLE 1(±)-2-Azabi- cyclo-[2.2.1]- X hept-5-en-3- Amino- Additive X equiva- onealcohol Example Y mmol lents % yield 1.7.1 — — — 15 52 1.7.2 water 17.11.25 23.3 67.5 1.7.3 water 34.3 2.5 32.3 58.3 1.7.4 methanol 34.3 2.54.5 83.1 1.7.5 ethanol 34.3 2.5 6.5 74.7 1.7.6 isopropanol 34.3 2.5 28.152.3

1.8. Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene withvarious amounts of methanol

Using the procedure of Example 1.7, the reaction was 5 carried out in avariety of methanol concentrations. The results are given in Table 2.TABLE 2 (±)-2-Azabi- cyclo[2.2.1]- Methanol hept-5-en-3- Amino- Methanolequiva- one alcohol Example mmol lents % yield 1.8.1 9.2 1 27.5 44.81.8.2 18.3 2 13.1 66.8 1.8.3 27.5 3 24.7 54.8 1.8.4 36.6 4 5.7 56.81.8.5 45.8 5 12.0 58.3 1.8.6 55.0 6 7.2 33.0

1.9 Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene withvarious solvents

Using the procedure of Example 1.7, the reaction was carried out in avariety of solvents (7.5 ml) and the content was determined. The resultsare given in Table 3. TABLE 3 (±)-2-Azabi- cyclo-[2.2.1]- hept-5-en-3-Amino- one alcohol Example Solvent X % Yield 1.9.1 dioxane 13.6 79.81.9.2 diethyl ether 10.8 68.6 1.9.3 tetrahydrofuran 22.4 67.6 1.9.4diisopropyl ether 12.6 51.3 1.9.5 tert-butyl methyl ether 10.0 71.31.9.6 monoglyme 15.5 75.3 1.9.7 formaldehyde dimethyl 12.0 74.2 acetal

1.10 Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene withvarious additions of LiBH₄

Following the procedure of Example 1.7, the reaction was carried outusing a variety of LiBH₄ concentrations, and the content was determined.The results are given in Table 4. TABLE 4 (±)-2-Azabi- cyclo-[2.2.1]-LiBH₄ hept-5-en-3- Amino- LiBH₄ equiva- one alcohol Example mmol lents %yield 1.10.1 4.6 1 11.9 47.9 1.10.2 6.9 1.5 9.6 45.6 1.10.3 9.2 2 12.771.3 1.10.4 11.5 2.5 13.3 74.5 1.10.5 13.8 3 12.8 77.1 1.10.6 16.1 3.512.7 62.4

1.11 Preparation (1R,4S)- and(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene in the presence ofvarious alcohols and in the presence of water in a variety of solvents

A 10 ml round-bottom flask fitted with magnetic stirrer was charged with0.50 g (4.6 mmol) of (±)-2-azabicyclo[2.2.1]hept-5-en-3-one and 0.30 g(13.7 mmol) of lithium borohydride in 6 ml of a variety of solvents, andthe mixture was heated to 60° C. At this temperature, over the course of30 min, 34.3 mmol of the additive Y were added dropwise using a syringe.The mixture was then stirred for 2 h at 60° C., cooled to about 20° C.and poured onto about 10 ml of semi-concentrated HCl.

The content is determined directly using a quantitativeion-chromatographic method (cf. Table 5). The ee value of the productwas determined by means of HPLC. The results are given Table 5. TABLE 5(−)-2-Azabi- (+)-2-Azabi- cyclo-[2.2.1] cyclo-[2.2.1] hept-5-en-3-onehept-5-en-3-one Aminoalcohol Example ee value Solvent Additive Y Yield(IC) ee value (HPLC) 1 98.0 dioxane water 64.3 >99.0 2 98.0 glyme water68.0 >99.0 3 75.9 dioxane water 65.1 76.0 4 75.9 glyme water 63.5 75.6 550.2 dioxane water 74.8 51.4 6 51.6 glyme water 64.1 53.0 7 25.3 dioxanewater 61.1 30.4 8 25.6 glyme water 61.0 29.6 9 98.0 dioxane methanol83.1 98.2 10 98.0 glyme methanol 81.5 99.2 11 75.9 dioxane methanol 81.478.0 12 76.2 glyme methanol 79.9 78.6 13 50.4 dioxane methanol 81.3 54.414 51.5 glyme methanol 82.0 55.2 15 24.8 dioxane methanol 65.2 27.4 1627.8 glyme methanol 81.7 32.2 17 98.0 dioxane ethanol 80.8 80.8 18 98.0glyme ethanol 85.1 85.1 19 75.5 dioxane ethanol 85.3 78.2 20 75.6 glymeethanol 83.6 78.4 21 50.7 dioxane ethanol 76.3 54.4 22 51.1 glymeethanol 71.3 55.2 23 25.4 dioxane ethanol 73.0 28.6 24 25.5 glymeethanol 75.0 28.6 25 98.0 dioxane water 62.0 >99.0 26 98.0 glyme water59.5 >99.0 27 51.3 dioxane water 79.0 52.2 28 49.0 glyme water 61.3 52.029 98.0 dioxane methanol 77.2 >99.0 30 98.0 glyme methancl 80.0 >99.0 3149.0 dioxane methanol 80.8 46.8 32 49.5 glyme methanol 80.9 48.8

1.12 Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene usingsodium borohydride in various alcohols

Following the procedure of Example 1.7, the reaction was carried out ina variety of alcohols. In contrast to Example 1.7, however, sodiumborohydride (0.51 g, 13.7 mmol) was used as reducing agent. The resultsare given in Table 6. TABLE 6 (±)-2-Azabi- cyclo-[2.2.1]- X hept-5-en-3-Amino- Additive X equiva- one alcohol Example Y mmol valents Yield % y1.12.1 water 17.1 1.25 75.4 20.1 1.12.2 water 34.3 2.5 71.9 26.7 1.12.3methanol 34.3 2.5 39.2 22.2 1.12.4 ethanol 34.3 2.5 67.8 8.6 1.12.5 — —— 62.2 3.5

1.13 Preparation of (±)-1-amino-4-(hydroxymethyl)-2-cyclopentene usingNaBH₃CN

60 ml of dioxane and 8.6 g (137 mmol) of sodium cyanoborohydride and11.9 g (137 mmol) of lithium bromide were refluxed overnight for 15 h at110° C. in a 100 ml sulphonation flask. The mixture was then cooled to60° C., and a solution of 5.0 g (45.8 mmol) of(±)-2-azabicyclo[2.2.1]hept-5-en-3-one containing 15 ml of methanol wereadded dropwise over the course of 30 min. The white suspension wasstirred for 3 h at 60° C., cooled to about 5° C. and poured into about100 ml of semi-concentrated HCl. The content was then determineddirectly using a quantitative ion-chromatographic method. The yield ofaminoalcohol was about 4%.

Example 2 Alkaline hydrolysis ofacetyl-(±)-1-amino-4-(hydroxy-methyl)-2-cyclopentene

88.9 g of racemic acetyl-1-amino-4-(hydroxymethyl)-2-cyclopentene(content 77.2%) were suspended (partially dissolved) in 70 g of water.84 g of 30% NaOH (1.1 equivalents) were added thereto, and the solutionwas refluxed for 3 h. According to TLC, the hydrolysis was complete. Theresulting acetate was removed by electrodialysis. The obtained aqueoussolution was reduced by evaporation and dried by azeotropic distillationwith butanol. The residue was taken up in methanol for racemateresolution. Yield of hydrolysis to(±)-1-amino-4-(hydroxymethyl)-2-cyclopentene was 90%.

Example 3 Preparation of (1R,4S)- or(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene 3.1 Racemate resolutionusing hydrolases 3.1.1 Preparation of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene using lipases

3.1.1.1 25 mM of racemic 1-amino-4-(hydroxymethyl)-2-cyclopentene weresuspended with 1000 units of Novozym 435 in 5 ml of dioxane at roomtemperature. 25 mM of ethyl methoxyacetate were added as acetylatingagent. The formation of N-methoxyacetylaminoalcohol was unambiguouslydetected by TLC. The conversion was 50% (according to estimation of theTLC). This reaction produced(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene.

3.1.1.2 50 mM of racemic 1-amino-4-(hydroxymethyl)-2-cyclopentene weresuspended with 1000 units (U) of Novozym 435 in 5 ml of tetrahydrofuran.50 mM of NaOH and 50 mM of ethyl methoxyacetate were added, and themixture was incubated at 30° C. N-Methoxyacetylaminoalcohol was detectedusing TLC. The estimated conversion was 50%. This reaction produced(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene.

3.1.1.3 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.06 ml of tributyrin(glyceryl tributyrate) and 20 U of Novozym 435 (immob. lipase fromCandida antarctica) at room temperature. After 3 days, enantiomericallypure, according to HPLC,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene was obtained in 43%yield.

3.1.1.4 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether. 0.02 ml of6-caprolactone and 20 U of Novozym 435 (immob. lipase from Candidaantarctica) at room temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 87% ee wasobtained in 49% yield (HPLC).

3.1.1.5 100 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of hexane, 0.3 ml of tributyrin and 20 U ofNovozym 435 (immob. lipase from Candida antarctica) at room temperature.After 1 week, (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 77%ee was obtained in 28% yield (HPLC).

3.1.1.6 100 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of tert-butanol, 0.3 ml of tributyrin and 20 U ofNovozym 435 (immob. lipase from Candida antarctica) at 30° C. After 1week, (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 78% ee wasobtained in 15% yield (HPLC).

3.1.1.7 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.2 mmol of methylcaproate and 20 U of Novozym 435 (immob. lipase from Candida antarctica)at room temperature. After 4 days(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 68% ee wasobtained in 52% yield (HPLC).

3.1.1.8 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.2 mmol of glycoldibutyrate and 40 U of Novozym 435 (immob. lipase from Candidaantarctica) at room temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 89% ee wasobtained in 31% yield (HPLC).

3.1.1.9 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.2 mmol of diethylfumarate and 40 U of Novozym 435 (immob. lipase from Candida antarctica)at room temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 86% ee wasobtained in 36% yield (HPLC).

3.1.1.10 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.2 mmol of diethylmalonate and 40 U of Novozym 435 (immob. lipase from Candida antarctica)at room temperature. After 4 days, (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 86% ee was obtained in 21% yield (HPLC).

3.1.1.11 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of diisopropyl ether, 0.2 mmol of tributyrin and40 U of Novozym 435 (immob. lipase from Candida antarctica) at roomtemperature. After 4 days, enantiomerically pure(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene was obtained in 15%yield (HPLC)

3.1.1.12 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of diisopropyl ether, 0.2 mmol of diethylfumarate and 40 U of Novozym 435 (immob. lipase from Candida antarctica)at room temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 88% ee wasobtained in 24% yield (HPLC).

3.1.1.13 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of diisopropyl ether, 0.2 mmol of diethylmalonate and 40 U of Novozym 435 (immob. lipase from Candida antarctica)at room temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 82% ee wasobtained in 14% yield (HPLC).

3.1.1.14 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of diisopropyl ether, 0.2 mmol of diethyldiglycolate and 40 U of Novozym 435 (immob. lipase from Candidaantarctica) at room temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 88% ee wasobtained in 7% yield (HPLC).

3.1.1.15 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of dibutyl ether, 0.2 mmol of tributyrin and 40 Uof Novozym 435 (immobilized lipase from Candida antarctica) at roomtemperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 95% ee wasobtained in 13% yield (HPLC).

3.1.1.16 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of pyridine, 0.02 ml of ethyl 2-methoxyacetateand 20 mg of lipase AK (lipase from Pseudomonas fluorescens) at roomtemperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 84% ee wasobtained in 18% yield (HPLC).

3.1.1.17 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.2 mmol of ethylcyanoacetate and 10 mg of lipase PS (lipase from Pseudomonas cepacia) atroom temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 67% ee wasobtained in 40% yield (HPLC).

3.1.1.18 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl tert-butyl ether, 0.2 mmol of diethylfumarate and 10 mg of lipase PS (lipase from Pseudomonas cepacia) atroom temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 86% ee wasobtained in 18% yield (HPLC).

3.1.2 Preparation of (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopenteneusing proteases

3.1.2.1 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of 2-methyl-2-butanol, 0.2 mmol of diethylmaleate and 40 mg of Alcalase (protease from Bacillus licheniformis) atroom temperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 28% ee wasobtained in 39% yield (HPLC).

3.1.2.2 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of 2-methyl-2-butanol, 0.2 mmol of diethylfumarate and 40 mg of Savinase (protease from Bacillus sp.) at roomtemperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 32% ee wasobtained in 42% yield (HPLC).

3.1.2.3 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of 2-methyl-2-butanol, 0.06 ml of tributyrin and20 mg of Savinase (protease from Bacillus sp.) at room temperature.After 4 days, (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 22%ee was obtained in 39% yield (HPLC).

3.1.2.4 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of 2-methyl-2-butanol, 0.06 ml of tributyrin and20 mg of subtilisin (protease from Bacillus licheniformis) at roomtemperature. After 4 days,(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 23% ee wasobtained in 36% yield (HPLC).

3.1.3 Preparation of (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopenteneusing proteases

3.1.3.1 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of hexane, 0.06 ml of tributyrin and 120 U ofSavinase (protease from Bacillus sp.) at room temperature. After 3-6days, (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 44% ee wasobtained in 46% yield (HPLC).

3.1.3.2 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of hexane, 0.06 ml of tributyrin and 20 mg ofAlcalase (protease from Bacillus licheniformis) at room temperature.After 3-6 days, (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene with44% ee was obtained in 35% yield (HPLC).

3.1.4 Preparation of (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopenteneusing lipases

3.1.4.1 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of 2-methyl-2-butanol, 0.03 ml of ethyl butyrateand 20 mg of Newlase F (lipase from Rhizopus niveus) at roomtemperature. After 1 week,(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 39% ee wasobtained in 37% yield (HPLC).

3.1.4.2 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of pyridine, 0.06 ml of tributyrin and 20 mg oflipase AK (lipase from Pseudomonas fluorescens) at room temperature.After 1 week, (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 30%ee was obtained in 10% yield (HPLC).

3.1.4.3 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of 2-methyl-2-butanol, 0.06 ml of tributyrin and20 mg of lipase AY (lipase from Candida rugosa) at room temperature.After 1 week, (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentenewith32% eewas obtained in 13% yield (HPLC).

3.1.4.4 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl t-butyl ether, 0.06 ml of tributyrinand 20 mg of lipase PS-CI (immobilized lipase from Pseudomonas cepacia)at room temperature. After 1 week,(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 29% ee wasobtained in 16% yield (HPLC).

3.1.4.5 11 mg of racemic cis-1-amino-4-(hydroxymethyl)-2-cyclopentenewere stirred with 1 ml of methyl t-butyl ether, 0.06 ml of tributyrinand 20 mg of lipase PS (lipase from Pseudomonas cepacia) at roomtemperature. After 1 week,(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene with 24% ee wasobtained in 22% yield (HPLC).

3.2 Racemate resolution using D-(−)-tartaric acid

3.2.1 A mixture of 8 g (70.6 mmol) of racemic1-amino-4-(hydroxymethyl)-2-cyclopentene and 10.6 g (70.6 mmol) ofD-(−)-tartaric acid in 186 g of methanol were dissolved at the refluxtemperature. The mixture was then cooled to 20° C. over 2 h. At 43° C.,seed crystals of the pure(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene D-hydrogentartrate wereadded. The crystallized product was filtered off and dried. Yield: 8.49g (45.6% based on racemic starting material) of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene D-hydrogentartrate, eevalue: 91.1%. For purification, 8.49 g (32.25 mmol) of thehydrogentartrate were suspended in 30 ml of methanol, and 2 equivalentsof 30% sodium methoxide were added. The sodium tartrate was filtered offand the methanol was distilled off.

The residue was taken up in 35 ml of pentanol. Then, at 55° C., 1.5 g ofHCl were introduced, and the solution was slowly cooled. At 40° C., thesolution was seeded with(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene hydrochloride. 45 ml ofacetone were then metered in, and the suspension was slowly cooled to 0°C. and filtered, and the residue was dried. 3.91 g of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene hydrochloride having anee value of >98% were obtained, corresponding to a yield, based onracemic (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene used, of 37%.

3.2.2 A mixture of 64 g of racemic1-amino-4-(hydroxymethyl)-2-cyclopentene (0.5 mol) and 75.2 g ofD-(−)-tartaric acid in 1330 g of methanol was dissolved at the refluxtemperature and then cooled to 20° C. over 2 h. At 43° C., seed crystalsof the pure 1R,4S-enantiomer were added. The crystallized product wasfiltered off and dried. Yield: 63.2 g (48.0% based on racemic1-amino-4-(hydroxymethyl)-2-cyclopentene) of(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene hydrogentartrate, eevalue: 91.1%. The ee value in the mother liquor was 76.0%.

3.2.3 Recrystallization of 1R,4S-(4-amino-2-cyclopenten-1-yl)methanolD-hydrogentartrate

61.84 g of 1R,4S-(4-amino-2-cyclopenten-1-yl)-methanolD-hydrogentartrate (0.235 mol, ee value 91.1%) were dissolved in 752 gof methanol under reflux. The solution was cooled to 20° C. within 90min, then the product was filtered off and washed with 64 g of coldmethanol. Drying gave 54.56 g of1R,4S-(4-amino-2-cyclopenten-1-yl)-methanol D-hydrogentartrate wereobtained, ee value 99.4% (yield 88.2%, 42.3% based on racemic1-amino-4-(hydroxymethyl)-2-cyclopentene). This was used tel quel in thechloropurine synthesis.

3.2.4 Following the procedure of Example 3.2.2, but using 223 g ofmethanol and seeding at 50° C., the racemate was separated. The yieldwas 7.98 g (42.9% based on racemic(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene used).

3.3 Racemate resolution using L-(+)-tartaric acid

3.3.1 A mixture of 8 g (70.6 mmol) of racemic1-amino-4-(hydroxymethyl)-2-cyclopentene and 10.6 g (70.6 mmol) ofL-(+)-tartaric acid in 186 g of methanol were dissolved at the refluxtemperature. The mixture was then cooled to 20° C. over 2 h. At 43° C.,seed crystals of the pure(1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopentene L-hydrogentartrate wereadded. The crystallized (1S,4R)-1-amino-4-(hydroxymethyl)-2-cyclopenteneL-hydrogentartrate was filtered off and dried. (ee value: 91.1%). 14 gof 30% methanolic sodium methoxide were added to the mother liquor, thenthe methanol was evaporated. The residue was taken up in 35 ml ofisobutanol, and the insoluble sodium tartrate was filtered off. At 55°C., 2 g of gaseous HCl were introduced into the filtrate. 38 ml ofacetone were then added, and the mixture was left to cool to 10° C. overthe course of 1 h. After 1 h, the(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene hydrochloride wasfiltered off with suction and washed with 8 ml of acetone. Drying underreduced pressure gave the(1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene hydrochloride in ayield of 34 g, 31.6% based on racemic1-amino-4-(hydroxymethyl)-2-cyclopentene with an ee value of >98%.

Example 4 Preparation of (1R,4S)-amino-4-(hydroxymethyl)-2-cyclopentenehydrochloride 4.1 Reduction of (−)-2-azabicyclo[2.2.1]hept-5-en-3-one

A 2 l autoclave (stainless steel type V4A) rendered inert with N₂, wascharged with 61.4 g of sodium borohydride 97.5% (1.623 mol), 70.2 g oflithium chloride 98.5% (1.656 mol), 13.2 g of Celite and 1410 g oftetrahydrofuran. The autoclave was closed and heated to an internaltemperature of 130° C. and the contents stirred for 4.5 hours at thistemperature (max. 8.0 bar).

After the autoclave had been cooled to about 60° C., the sodium saltsinsoluble in tetrahydrofuran (NaCl, NaBH₄) were filtered off. These werewashed with 353 g of tetrahydrofuran, and the combined filtrates werereduced to about half in a stirred 1 l glass vessel by distillation atatmospheric pressure (distillate 1: about 710 g of tetrahydrofuran).

Further distillation, alternating with the portionwise addition of atotal of 936 g of dioxane then completed the solvent exchange(distillate 2: about 1289 g of tetrahydrofuran/dioxane).

The LiBH₄ suspension was cooled to about 60° C., and 56.7 g of(−)-2-azabicyclo[2.2.1]hept-5-en-3-one (97.5%) were added.

Starting at about 60° C., 132.5 g of methanol were metered in in exactlyone hour at a rate such that a temperature range of 58-62° C. wasmaintained The mixture was then allowed to react for a further hour at60° C. A further 397.0 g of methanol were then added (sample comprisesan analytical yield of 70.5%), and the contents of the stirred vesselwere cooled to 0° C. At this temperature, 90.0 g of HCl were introducedinto the reaction mixture (slightly exothermic) and stirring wascontinued for a further hour at about 0° C. Distillation at atmosphericpressure (up to a head temperature of 75° C.) removed the low-boilingfractions (methanol, borate) and about 70% of the dioxane (distillate 3:about 1093 g). Distillation under reduced pressure (about 30 mbar),alternating with the portionwise addition of a total of 282 g of1-pentanol then completed the solvent exchange (distillate 4: about 240g of dioxane/pentanol).

After a further 302 g of 1-pentanol had been added, the mixture wasstirred for 1 hour at 50° C., and precipitated salts, about 39 g moistweight, were filtered off and washed with 200 g of 1-pentanol. Thecombined filtrates were reduced by redistillation under reduced pressure(about 20 mbar) (distillate 5: 235 g of 1-pentanol). Then, at about 50°C., 236 g of acetone were metered in, and the reaction mixture wasseeded with a few crystals of(1R,4S)-amino-4-(hydroxymethyl)-2-cyclopentene. The mixture was cooledto 5° C. over the course of 1 hour, and crystallization was completed bystirring the mixture for a further 6 h at 5° C.

The crystals were filtered off, washed with 63 g of acetone and dried ata max. 50° C. in a vacuum drying cabinet (10 mbar). This gave 83.5 g ofcrude product* (content: 56.5%).

This corresponded to a yield of 61.4% based on(−)-2-azabicyclo[2.2.1]hept-5-en-3-one used.

4.2 Reduction of (±)-2-azabicyclo[2.2.1]hept-5-en-3-one

A 2 1 autoclave (stainless steel type V4A) rendered inert with N₂, wascharged with 41.56 g of sodium borohydride 97.5% (1.071 mol), 51.48 g oflithium chloride 98.5% (1.196 mol), 9.30 g of Celite and 955.0 g oftetrahydrofuran. The autoclave was closed and heated to an internaltemperature of 130° C. and the contents stirred for 6 hours at thistemperature (max. 6.3 bar).

After the autoclave had been cooled to about 60° C., the sodium saltsinsoluble in tetrahydrofuran (NaCl, NaBH₄) were filtered off. These werewashed with 239.0 g of tetrahydrofuran, and the combined filtrates werereduced to about half in a stirred 1 l glass vessel by distillation atatmospheric pressure. (distillate 1: about 590 g of THF). Furtherdistillation, alternating with the portionwise addition of a total of661.0 g of dioxane then completed the solvent exchange (distillate 2:about 685 g of tetrahydrofuran/dioxane)

The LiBH₄ suspension was cooled to about 60° C., and 36.0 g of2-azabicyclo[2.2.1]hept-5-en-3-one (97.5%) were added.

Starting at about 60° C., 77.6 g of methanol were metered in in exactlyone hour at a rate such that a temperature range of 58-62° C. wasmaintained. The mixture was then allowed to react for a further hour at60° C. A further 233.0 g of methanol were then added, and the contentsof the stirred vessel were cooled to 0° C. At this temperature, 52.9 gof HCl were introduced into the reaction mixture (slightly exothermic)and stirring was continued for a further hour at about 0° C.Distillation at atmospheric pressure (up to a head temperature of 75°C.) removed the low-boiling fractions (methanol, borate) and about 70%of the dioxane (distillate 3: about 700 g). Distillation under reducedpressure (about 30 mmol), alternating with the portionwise addition of atotal of 169.4 g of 1-pentanol then completed the solvent exchange(distillate 4: about 183 g of dioxane/pentanol). After a further 127.1 gof 1-pentanol had been added, the mixture was stirred for 1 hour at 50°C., and precipitated salts, about 41 g moist weight, were filtered offand washed with 63.5 g of 1-pentanol. The combined filtrates werereduced by redistillation under reduced pressure (about 20 mbar)(distillate 5: 235 g of 1-pentanol) Then, at about 50° C., 238.0 g ofacetone were metered in, and the reaction mixture was seeded with a fewcrystals of aminoalcohol hydrochloride salt. The mixture was cooled to5° C. over the course of one hour, and crystallization was completed bystirring the mixture for a further 6 hours at 5° C.

The crystals were filtered off, washed with 61.0 g of acetone and driedat a max. 50° C. in a vacuum drying cabinet (10 mbar). This gave 50.0 gof crude product (content: about 50% of aminoalcohol hydrochloridesalt).

This corresponded to a yield of 52.0% based on2-azabicyclo[2.2.1]hept-5-en-3-one used.

Example 5 Preparation of acylated aminoalcohols 5.1 Preparation of(1R,4S)-N-BOC-1-amino-4-(hydroxymethyl)-2-cyclopentene(BOC=tert-butoxycarbonyl)

75 g of a solution of (1R,4S)-1-amino-4-hydroxmethyl-2-cyclopentene wereadjusted to pH 8 using 30% strength NaOH, and 6 g of NaHCO₃ were addedto the mixture. The mixture was heated to 52° C. Whilst stirring themixture thoroughly, 60 ml of diisopropyl ether were added thereto andthen, over the course of 2 h, a solution of 11.12 g of BOC anhydride in18.2 ml of diisopropyl ether were metered in. The mixture was filteredover Celite, and the phases were separated. The aqueous phase wasextracted with 65 ml of diisopropyl ether. The combined organic phaseswere washed with 45 ml of water, then evaporated to 37.5 g and heated to50° C. 31 ml of n-hexane were added dropwise to the solution. After themixture had been slowly cooled to 0° C. (2 h), the title compound wasfiltered, washed with 12 ml of n-hexane/diisopropyl ether 1/1 and dried.This gave 6.75 g of product. The yield was 71%.

5.2 Preparation of(1R,4S)-N-acetyl-1-amino-4-(hydroxymethyl)-2-cyclopentene

25 g (1R,4S)-1-amino-4-(hydroxymethyl)-2-cyclopentene hydrochloride weredissolved in 182 ml of acetic anhydride, and at 0° C., a solution of18.25 g of triethylamine in 60 ml of acetic anhydride were addedthereto. The mixture was stirred at 80° C. for 3 h, then cooled to roomtemperature. The triethylamine hydrochloride was filtered off and washedwith 120 ml of n-hexane. The filtrate was evaporated. 300 ml of toluenewere added to the residue, and the mixture was stirred at roomtemperature in the presence of 5.2 g of activated carbon and 13 g ofCelite for 20 min. The mixture was then filtered, and the filter cakewas washed (3×40 ml of toluene), and the solvent was completelyevaporated. 180 ml of methanol and 15.5 g of K₂CO₃ were added to theresidue, and the mixture was stirred at room temperature for 10 h. Thesuspension was filtered off and the filtrate evaporated. The residue wassuspended in 750 ml of isopropyl acetate and boiled in the presence of0.5 g of activated carbon to reflux for 1.5 h. Following filtration ofthe activated carbon (70-80° C.), the filtrate was cooled at 0° C.overnight. The title compound was filtered, washed with 80 ml of coldisopropyl acetate and dried under reduced pressure to give 17.2 g ofproduct. The yield was 66%.

5.3 Preparation of(1R,4S)-N-butyryl-1-amino-4-(hydroxymethyl)-2-cyclopentene

34.7 g of (1R,4S)-1-amino-4-hydroxymethyl-2-cyclopentene hydrochlorideand 2 g of N,N-4-dimethylaminopyridine were dissolved in 600 ml ofmethylene chloride. The solution was cooled to 0° C. 52 g oftriethylamine were then added dropwise (5 min). The mixture was stirredfor a further 30 min. At 0° C., a solution of 35.2 g of butyryl chloridein 60 ml of methylene chloride was metered into the mixture over thecourse of 1 h. The mixture was stirred for a further 1.5 h at between 0and 20° C., and then 600 ml of water were added thereto. Following phaseseparation, the aqueous phase was extracted with 600 ml of methylenechloride. The combined organic phases were washed 3×500 ml of 10%strength NaOH, then completely evaporated. The dried solid was dissolvedin 120 ml of methanol. 5 g of K₂CO₃ were added to the solution, and themixture was stirred for a further 2 h at room temperature. The inorganicsalts were filtered off and washed with 20 ml of methanol. The filtratewas neutralized with 2N HCl. The suspension was filtered off, and thefilter cake was washed with 20 ml of methanol. The filtrate wascompletely evaporated. The solid residue was dried and crystallized in150 ml of toluene to give 28.5 g of the title compound. The yield was67%.

Example 6 Preparation of[4(R)-(2-amino-6-chloropurine-9-yl)cyclopent-2-ene-1(S)-yl]methanol 6.1Preparation of[4(R)-(2-amino-6-chloropurine-9-yl)-cyclopent-2-ene-1(S)-yl]methanolstarting from 1R,4S-(4-amino-2-cyclopenten-1-yl)methanolD-hydrogentartrate

47.4 g of 1R,4S-(4-amino-2-cyclopenten-1-yl)methanol D-hydrogentartrate(0.18 mol, ee >98%) in 200 ml of ethanol were introduced initially. Atroom temperature, 54.6 g of NaHCO₃ (0.65 mol) and 37.3 g (0.18 mol) ofN-(2-amino-4,6-dichloro-4-pyrimidyl)-formamide were added, boiled for 9h under reflux and then cooled to room temperature. The salts werefiltered off and then washed with 50 ml of ethanol. The filtrate wasconcentrated to 280 g on a rotary evaporator. 18.4 g of HCl gas wereintroduced into the resulting solution at T<25° C., then 95.5 g (0.9mol) of trimethyl orthoformate were added, and the whole was heated to40° C. (10 min). At this temperature, the mixture was seeded withchloropurine hydrochloride. After 2 h at 42° C., the productcrystallized out. The suspension was cooled to 15° C. The product wasfiltered and then washed with 3×50 ml of ethanol, then dried at 50° C.under reduced pressure. The yield was 41.9 g (75.8%). Beige powder,content (HPLC): 95.0%.

2.6 Preparation of[4(R)-(2-amino-6-chloropurine-9-yl)-cyclopent-2-ene-1(S)-yl]methanolstarting from (−)-2-azabicyclo[2.2.1]hept-5-en-3-one

A 2 l autoclave (stainless steel type V4A) rendered inert with N₂, wascharged with 61.4 g of sodium borohydride 97.5% (1.623 mol), 70.2 g oflithium chloride 98.5% (1.656 mol), 13.2 g of Celite and 1410 g oftetrahydrofuran. The autoclave was closed and heated to an internaltemperature of 130° C. and the contents stirred for 4.5 hours at thistemperature (max. 8.0 bar). After the autoclave had been cooled to about60° C., the sodium salts insoluble in tetrahydrofuran (NaCl, NaBH₄) werefiltered off. These were washed with 353 g of tetrahydrofuran, and thecombined filtrates were reduced to about half in a stirred 1 l glassvessel by distillation at atmospheric pressure (distillate 1: about 710g of tetrahydrofuran). Further distillation, alternating with theportionwise addition of a total of 936 g of dioxane then completed thesolvent exchange (distillate 2: about 1289 g oftetrahydrofuran/dioxane).

The LiBH₄ suspension was cooled to about 60° C., and 56.7 g of(−)-2-azabicyclo[2.2.1]hept-5-en-3-one (97.5%/0.507 mol) were added.

Starting at about 60° C., 132.5 g of methanol were metered in in exactlyone hour at a rate such that a temperature range of 58-6220 C. wasmaintained. The mixture was then allowed to react for a further hour at60° C. A further 397.0 g of methanol were then added (sample comprisesan analytical yield of 70.5%), and the contents of the stirred vesselwere cooled to 0° C. At this temperature, 90.0 g of HCl were introducedinto the reaction mixture (slightly exothermic) and stirring wascontinued for a further hour at about 0° C. The solution was evaporatedon a rotary evaporator at 50° C. under reduced pressure, 200 ml ofmethanol were added and the methanol was removed again (filtration withsuction of the methyl borate). The procedure was repeated using afurther 200 ml of methanol. 250 ml of ethanol were added to the oilobtained (253.4 g comprise 3.16% of aminoalcohol; this corresponded to0.360 mol), and the mixture was poured into a 1 l double-jacketedstirred vessel. At room temperature, 72.6 g of NaHCO₃ (0.86 mol) and74.6 g (0.360 mol) of N-(2-amino-4,6-dichloro-4-pyrimidyl)formamide wereadded, the mixture was refluxed for 9 h and cooled to room temperature,and the salts were filtered off and then washed with 100 ml of ethanol.The filtrate on the rotary evaporator was concentrated to 560 g. 63.4 gof HCl gas were introduced into the resulting solution at T<25° C., then191.0 g (1.80 mol) of trimethyl orthoformate were added, and the mixturewas heated to 40° C. (10 min). At this temperature, the mixture wasseeded with chloropurine hydrochloride, and left to crystallize for 2 hat 42° C. The suspension was cooled to 15° C. The product was filteredand then washed with 3×50 ml of ethanol, then dried at 50° C. underreduced pressure. The yield was 66.0 g (59.7%). Beige powder, content(HPLC) : 89.3%. This corresponded to a yield of 42.4% based on the Vincelactam used.

1-13. (canceled)
 14. (1R,4S)-1-Amino-4-(hydroxymethyl)-2-cyclopentene D-or L-hydrogentartrate. 15.(1S,4R)-1-Amino-4-(hydroxymethyl)-2-cyclopentene L- orD-hydrogentartrate.